A conventional particulate sensor for detecting the amount of particulate matter in exhaust gas of an internal combustion engine is disclosed, for instance, in Patent Document 1. This sensor includes electrodes that are disposed parallel to each other with a space in between. The sensor is installed in an exhaust path in such a manner that at least some portions of the electrodes are exposed to the exhaust gas. When the exhaust gas is discharged through the exhaust path, particulate matter in the exhaust gas deposits on the electrodes. This causes the impedance between the electrodes to change. The sensor disclosed in Patent Document 1 detects changes in the impedance to determine the amount of particulate matter deposited between the electrodes.